This paper exploits a natural experiment at the Erasmus University Rotterdam to evaluate the effectiveness of small-scale teaching groups that are typically used at universities in undergraduate courses. Economic Bachelor students who had a GPA below a seven in their first Bachelor year, were obliged to attend 70% of the tutorials per course in their second year. We use a regression-discontinuity design to identify the intention-to-treat effect of the policy as well as a well-defined local average treatment effect of actual attendance on grades. During the lunch seminar I will present preliminary findings. We find that the policy of mandatory tutorials caused an increase in attendance of second year Bachelor students of roughly 20%. Remarkably, point estimates for the intention-to-treat are consistently negative, but small, and mostly statistically significant. In addition, we find a negative effect of attendance upon grades, sometimes statistically significant.